Several weeks after the incidents were reported to have taken place, Beijing's state-run media broke its silence this week, slamming what it called a serious attack on satellite broadcasting and a threat to national security.

Media and state officials accused the "overseas cult organization of Falun Gong" and its U.S.-based leader, Li Hongzhi.

The U.S.-based information center for Falun Gong, which describes itself as a meditation sect, said it had no knowledge of the broadcasts, but that previous such attempts had come from grassroots Falun Gong practitioners inside China.

According to the center, it was aware of seven separate occasions over the past six months where adherents had "overridden state-run cable television signals with footage revealing the truth about [President] Jiang Zemin's persecution of Falun Gong and demonstrating the true nature of the practice."

It was reported from Hong Kong Wednesday that police in the semi-autonomous territory - where Falun Gong remains legal - had joined an investigation into the latest broadcasts.

Last month's incidents took place, Chinese media said, at a time when rural viewers were trying to watch "the fifth anniversary of Hong Kong's return to China, the World Cup finals and other major domestic and international news."

The interruptions happened between June 23-30. The Hong Kong event was on July 1, while the final fixtures in the World Cup soccer tournament were held in the closing days of the month.

The reports quoted senior broadcast officials as saying the Chinese-run Sinosat satellite and channels used to broadcast programs to remote parts of the country had been affected.

Images bearing Falun Gong propaganda material had appeared on nine China Central Television Station (CCTV) channels and 10 provincial television channels.

"This was a serious attack on satellite broadcasting and on international regulations," said Ministry of Information Industry representative Liu Lihua. "This despicable act should be condemned by the entire international community."

China Daily said Tuesday images of "cult activities" had been screened.

Reports at the time said the broadcasts had also included the slogan: "Falun Dafa is good." Falun Dafa is another name for the meditation and exercise system, which claims millions of practitioners around the world but has been designated an "evil cult" by Beijing.

The movement is the subject of a severe government crackdown. Hundreds have been arrested in China, and the information center claims to have verified the deaths of 430 practitioners in police custody.

In a statement released by the Xinhua news agency, the Information Industry Ministry said the broadcasts had endangered China's national security.

Interference with signals, it said, could disrupt "aviation and maritime communications and navigation and emergency rescue operations. The consequences would be dreadful to contemplate."

The ministry said the international community should condemn the actions and "jointly take measures to crack down on such evil behavior."

Du Baichuan, vice-president of the China Satellite Users Society, called the incident "an overt challenge to modern civilized society and ... a flagrant subversion of social order and public morality."